If you've truly never taken any of the drugs insist it be sent to an actual lab for further testing. When they get positives they usually do that anyway.
It's pretty hard to get something past anymore than a simple 5 panel UA. An expanded 10 panel is pretty much a lock to be right. Pain management drs are monitored closely by the DEA and their records are maintained with the utmost of accuracy. They won't risk their livelihood over a drug test. If it goes to the lab they send questionable results to the final results there should be accurate.
I suppose anything is possible but these drs have too much at stake with testing. They seldom make a mistake. Good luck and God bless.
I am not a dr. My statements are based on years of experience and related education. Consult with the professional of your choice regarding matters of concern.